440 Birge—Vertical Distribution of Pelagic Crustacea . 
Table G — Table showing the percentage of each form of Crustacea by 
periods and levels. 
Diaptomus. 
Cyclops. 
Depth. 
Period. 
Period. 
Meters. 
I. 
II. 
III. 
I IV. 
Av. 
I 
]I. 
III. 
IV. 
Av. 
0—3... 
84.0 
75.6 
62.68 
57'. 5 
69 
10.57 
22.5 
33.92 
38.2 
26 
3—6... 
83.87 
68.5 
61.24 
53.4 
65 
10.75 
28 
35.42 
42.4 
31 
6-9 .. 
72.32 
57 
59.72 
52.8 
59 
16.7 
30.6 
- 
32.20 
42.1 
32 
9-12.. 
44.78 
22.9 
28.89 
50.9 
36.5 
26.49 
49.4 
61.48 
42.5 
48.3 
12—15.. 
20. 
2 
6.25 
63 
11.5 
31.2 
54 
83.33 
37 
55.7 
15—18 . 
69.56 
83 
33.33 
55 
57 
8.70 
17 
66.67 
33 
30 
Av... 
78.56 
69.3 
59.26 
1 
53.3] 
| 
| 64 
1 
12.92 
26.2. 
| 36.15 
40.5 
30.5 
Daphnia hyalina. 
Daphnia pulicaria. 
Depth. 
Period. 
Period. 
Meters. 
I. 
H. 1 
III. 
IV. 
Av. 
I. 
II. 
III 
IV. 
Av. 
0-3... 
5.37 
1.7 
3.4 
4.1 
3 
05 
.08 
0 
0 
.06 
3—6... 
5.09 
2.9 
3.17 
4 
3.4 
.28 
.5 
.17 
0 
3 
6-9... 
7.68 
5 
3.32 
4.5 
4.6 
3.29 
6 
4.75 
.4 
3.7 
9-12.. 
16.42 
2.1 
.74 
3.6 
3.5 
12.31 
25.5 
8.89 
2 9 
11.5 
12—15.. 
11.11 
2 
6.25 
0 
4 
37 78 
3.9 
4.17 
0 
30.7 
15-18.. 
13.03 
0 
0 
11 
14 
8.7 
0 
0 
0 
0 
Av. .. 
6.44 
2.3 
3.15 
4.2 
3.3 
2.08 
2 
1.44 
.3 
1.5 
THE DISTRIBUTION OF THE CRUSTACEA IN DETAIL. 
Diaptomus oregonensis Lillj. 
Number .—This species was by far the most numerous of the 
Crustacea taKen during July in lake Mendota, and at the same 
time was the species whose vertical distribution was most dis¬ 
tinctly marked. The average total catch of Diaptomus for the 
